In a typical hydraulic fracturing operation, a fracturing fluid containing a solid proppant is pumped into a formation penetrated by a wellbore at a sufficient pressure to cause the formation or enlargement of fractures in the reservoir. Typically, the subterranean formation has a plurality of productive zones. During production of fluids from the well, it usually is desirable to establish communication with selected zones such that stimulation treatments do not inadvertently flow into a non-productive zone or a zone of diminished interest. Selective stimulation becomes pronounced as the life of the well declines and productivity of the well decreases.
Reservoir monitoring is used to assess the productivity of zones or formations from which fluids are being produced. In addition, monitoring of produced fluids is important in order to increase efficiency of the fracturing operation. In the past, tracers have been placed in packs in strategic areas within the well. Unfortunately, such monitoring methods of the prior art have a short lifetime following placement of the tracer within the well. In addition, they do not provide a means for controlling the release of the tracer within the well. Alternatives have therefore been sought.
Alternatives have also been sought for introducing well treatment agents into a well such that the well treatment agent may be released over a sustained period of time. Well treatment agents are often used in production wells to prevent the deleterious effects caused by such deposits and precipitates. For instance, scaling in the formation (as well as in production lines downhole) is often controlled by the use of scale inhibitors.
Composites previously used include those wherein a well treatment agent is adsorbed onto a high surface area solid carrier material. Such composites may be used for the slow release of well treatment agents into the formation and the environs. They have been used in various formations including deepwater, tight gas and coal bed methane formations. U.S. Pat. No. 7,686,081 and U.S. Patent Publication No. 2010/0175875 disclose recharging such particles once they are depleted.
Such composites, however, often have an inherent drawback in that they do not exhibit the requisite strength of proppants and thus must usually be mixed at less than 10% by weight of the proppant in the fracture or sand control treatment. Higher loadings result in crushing of the composites translating into a loss of pack conductivity.
Recently, in U.S. Patent Publication No. 2012/0273197, herein incorporated by reference, a composite was disclosed which exhibited the strength of a proppant and which was capable of delivering a well treatment agent for an extended period of time into a treated formation. The cost of producing such composites is quite high. A less expensive alternative has therefore been sought.
It should be understood that the above-described discussion is provided for illustrative purposes only and is not intended to limit the scope or subject matter of the appended claims or those of any related patent application or patent. Thus, none of the appended claims or claims of any related application or patent should be limited by the above discussion or construed to address, include or exclude each or any of the above-cited features or disadvantages merely because of the mention thereof herein.